Pros
Stable, comfortable, nice people. You can get professional, specially in C#, and learn from very strong people.
Cons
Very hard to get promoted without selling your soul, and every free minute to the company, and not enough promotion options. Too large in my opinion, lots of bureaucracy. Lots of average employees, that are there to do their daily and no more, not ambitious enough. Lots of legacy code, maintenance, hard to be on a role that matters, because management wants to get all decisions pretty much. Not enough employees investment, like courses or meetups - only for managers and not enough either. This is not a cool startup with perks and cool people, more like a corporate feeling that is trying to be cool, but turns out pretty awkward.